Effect of magnetic softness in a soft layer on media properties of hard/soft stacked composite perpendicular media

Adding Pt into CoCr-oxide alloy for controlling magnetic softness in a soft layer on hard/soft (H/S) stacked composite media significantly affects magnetic properties and microstructure. Hc values for capping layer (CL) media with a relatively high-Hk soft layer initially increase with increasing tcap. However, Hc values are relatively constant for H/S media with Pt 3% and 10% soft layers and reduced for the media with a CoTaZr–SiO2 soft layer having in-plane Hk. The simulation results explain these experimental Hc trends by the compensation effect between the decrease in average Ku due to the use of less-Ku soft layer and the increases in volume with increasing tsoft. Reduction in Hc with increasing tsoft is anticipated when Ku in a soft layer reduces by >27%. As the Pt content in a soft layer increases from 3% to 18%, higher Hc and Hn but lower Hs are observed. Plan-view transmission electron microscopy images for the medium with Pt 18% soft layer show no subgrains and thinner grain boundary width and e...